Gas burner utilizing air above atmospheric pressure



1964 J. w. cLAYwELL ETAL 3,162,238

GAS BURNER UTILIZING AIR ABOVE ATMOSPHERIC PRESSURE Filed Oct. 9, 1961 United States Patent 3,162,238 GAS BURNER UTILIZING AIR ABOVE ATMOSPHERIC PRESSU Jack W. Claywell and Casimir J. Pavlalr, both of Wisconsin Rapids, Wis., assignors to Preway, Inc, a corporation of Wisconsin Filed Oct. 9, 1961, Ser. No. 143,736 1 Claim. (Cl. 158-89) This invention relates to a combustion system utilizing a gas burner and more particularly to a combustion system for a gas dishwasher in which the gas and air are thoroughly premixed.

An object of the invention is to provide a new and improved gas burner in which air above atmospheric pressure and gas are thoroughly premixed resulting in ignition of a fully mixed mixture not requiring any secondary air.

Another object of the invention is to provide a forced air gas burner comprising a burner mixing chamber, means for directing air above atmospheric pressure to said mixing chamber inlet, and a gas supply orifice downstream from said mixing chamber inlet opening toward said inlet whereby gas is directed in a direction counter to the flow of air to obtain mixing of the gas with the air and in which a target is located in the chamber against which the air and gas impinge.

Still another object of the invention is to provide a gas burner for a dishwasher having a tub with a bottom provided with a sump through which a tubular heat exchanger extends with the burner referred to above being located within said heat exchanger, ignition means for the fuel located in the heat exchanger embodying specifically a spark plug and a spiral member located within the heat exchanger for increasing the heat exchange rate.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIGURE 1 is a plan section of a gas dishwasher with a part of the tub bottom broken away with the section being taken at a level immediately above the tub bottom;

FIGURE 2 is a vertical section on an enlarged scale taken generally along the line 22 in FIGURE 1;

FIGURE 3 is a vertical section taken generally along the line 3-3 in FIGURE -2;

FIGURE 4 is a plan section taken generally along the line 4-4 in FIGURE 2 and showing a detail of the gas supply line and orifice therein; and

FIGURE 5 is a perspective view of the target.

While this invention is susceptible of embodiment in many difierent forms, there is shown in the drawings and will herein be described in detail an embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the inventionwill be pointed out in the appended claims.

A dishwasher embodying the invention is shown only in part herein and reference may be had to the copending application of Jack W. Claywell, Serial No. 28,895, filed May 13, 1960 and now Patent No. 3,104,669 for a more detailed showing of the dishwasher. The dishwasher embodies a cabinet having a back wall and side walls 11 and 12 with a suitable enclosing front wall (not shown) with a tub disposed therein having a tub bottom 15 in which is located a sump 16 disposed generally centrally of 3,152,238 Patented Dec. 22, 1964 the tub bottom and extending to a lower level to collect water utilized in the dishwashing cycle. A tubular heat exchange member 20 passes through the sump for transfer of heat derived from combustion to water located in the sump.

The combustion system associated with the heat exchanger 20 embodies a burner casing 30 having a cylindrical end 31 housing a flame stop in the form of a spirally wound corrugated ribbon 32 wound about a central solid core 33.

The burner casing 30 has a burner mixing chamber 35 terminating at the flame stop and having an inlet 36 connected to a combustion blower 40 located at a level beneath the heat exchange tube 20 by a vertically extending tube 41. The blower 40 directs air into the burner mixing chamber 35 through the inlet 36 at a pressure above atmospheric.

Gas is supplied to the burner and particularly into the chamber 35 downstream of the mixing chamber inlet 36 through a gas line 46. The gas line has an orifice 47 located within the chamber 35 which opens toward the mixing chamber inlet 36 whereby gas emitted under pressure through the orifice 47 flows in a direction counter to the flow of the air from the blower 40. Air and gas impinge upon a target 48 in the mixing chamber to obtain thorough mixing. The flow of gas counter to the direction of the flow of air and impingement of the air and gas on the target results in a thorough mix so that a mixture of gas and air passes through the flame stop for ignition therebeyond and within the heat exchanger 20.

The target 48 as shown in FIG. 5, has a central disc 49 supported from an attaching base 4911 by spaced apart legs 49b. Because of the mixing, fuel ignition means may be located at the periphery of the heat exchanger and, as shown in FIG. 2, this means embodies a spark plug indicated generally at 50 which is connected in a suitable circuit for causing a spark to occur at the desired time for igniting the fuel and air mixture.

The mixing also avoids any requirement for secondary air so that the entire combustion system is substantially sealed with the only source of air being from the blower 40. As is Well known in the art, the size of the orifice 47 in the gas supply line 46 may be varied and being dependent upon the gas being utilized and the heat requirements of the system.

Combustion takes place within the heat exchanger 20 in the area adjacent the flame stop 32 and the heat exchange rate is increased by the use of a spiral member 51 positioned within the heat exchanger and extending along a substantial part of the length thereof. The combustion gases are exhausted from the heat exchanger either through a suitable flue or returned to the room after dilution and reduction in temperature by mixture with room air.

In order to regulate the volume of air for a specific gas a removable member 52 is located at an end of the tube 41 and has an opening for control of air flow. Another member 52 with a different size opening can be used with a different gas.

We claim:

A gas burner utilizing air above atmospheric pressure for premix of gas and air Without requiring secondary air for combustion comprising, a generally cylindrical casing having a mixing chamber with an inlet and an outlet at opposite ends thereof, a combustion blower, means defining an air passage from said blower to said mixing chamber inlet; a gas line with an orifice within said -mix-' ing chamber for supplying gas under pressure, said orifice being positioned adjacent'the center of the casing and opening toward said mixing chamber inlet for counter-: fiow relative to said air into said mixing chamber to mix a and a flame stopeittending with said air, a target in the mixing chamber including a disc positioned centrally in the casing to have the air impinge against one side thereof and thegas'against the other side with both the air and gas moving radiallyputwardly forthorough intermixing across the, entire mixing chem: 5

her, said disc beingvof a size less than the casing and ex- I tending generally transversely thereof to define a generally annular ;air flow space between the disc and the casing, I

means defining a combustion chamber downstream of said 'mixing' chamber, 'fuel ignition means yin'said Com bustion chamber in the path of the gas and air mixture,

across the casing between said mixing chamber and said fuel ignition means.

References Cited in thefilej of this patent UNITED STATES PATENTS 1,446,666 Schulmeyer et a1 Feb. 27, 1923 1 2,220,572 Knu p ut Nov. 5, 1940 2,594,562 Jackson Apr. 29, 1952 2,641,206 Stout June 9, 1953 2,705,868 Forman -Apr. 12, 1955 2,712,308 Keating July 5, 1955 2,841,136 Pettit etal. July l, 1958 I I FOREIGN PATENTS I i 599,257 Great Britain -Mar. 9, 1948 803,885 France July 20, .1936 

